Diagnostics

Pure Tone Audiometry

The Pure Tone hearing test is used to provide a measure of hearing sensitivity and helps us determine the type and degree of hearing loss. Although it is an essential starting point, pure tone tests do not provide a clear depiction of the patients ability to process speech. Speech is complex and many factors impact on our ability to understand it, particularly in challenging or noisy environments. Fortunately, Cubex is one of the few audiology practices in the UK that test the cognitive processes related to hearing. Rather than just relying on a tonal stimulus to detect hearing, speech tests in quiet and in noise provide a better ‘Real World’ perspective of a person’s reduced hearing.

It makes sense to include a speech in noise test in the test battery. Not only does it provide an understanding of a person’s capacity to process speech in noise, the measure allows us to complete a functional forecast , provides valuable information to help with hearing aid selection and is used to demonstrate improvements in aided performance.

Multi frequency audiometry provides us with the opportunity to test more interoctave frequencies than in conventional tone audiometry. This is a particlularly useful tool for assessing steep slope high frequency hearing loss as it provides a more precise measure of how steeply the curve is actually sloping. It is also used in our evaluation of tinnitus, as is provides a means to match the tinnitus.

High Frequency PTA

Extended high frequency audiometry – above 8kHz – is more sensitive than conventional audiometry and can be used to detect early signs of hearing impairment and monitoring hearing losses that may have been caused by noise exposure.

Using a calibrated high frequency audiometry headset, this test is used routinely in our industrial audiology clinics and for impairments caused by ototoxicity, noise exposure, and acoustic traumas.

TEN (HL) Test

The TEN (HL) Test is used for diagnosing cochlear dead regions. The presence or absence of dead regions has siginificant implications for hearing aid fittings and functional forecasting as if an individual presents with a dead region, there may be little or no benefit in providing amplification to that region. It helps determine where to apply the amplification in order for the individual to experience some degree of benefit.

The TEN (HL) test can also be used in the process of determining candidacy for cochlear implants In the past, this test could only be performed by using an external CD player which had to wired into the Audiometer. Fortunately, this test is now available as a built in module in the Affinity 2.0.

Hearing care is not just about testing with pure tones or making sounds audible. Increasing speech intelligibility depends on so much more.

Rather than relying on a tonal stimulus to detect hearing, speech audiometry assesses the ability of an individual to discriminate speech. This provides a much better ‘real world’ perspective of an individual’s hearing loss. Furthermore, it carries additional diagnostic information as it is a good indicator of where in the auditory system the hearing pathology lies. This is important as the location of the hearing loss can relate to the functional benefit one will receive when aided. There are several important components to the speech audiogram which build on the information obtained from the pure tone audiogram or free field testing:

Maximum Speech Recognition Score: This allows you to see the maximum percentage of speech an individual is able to discriminate when the sounds are made louder above their hearing thresholds. This is important, as with some hearing losses although tone audiometry methods may suggest satisfactory hearing levels, the actual discrimination of the client may be significantly worse. This could lead to potential communication problems. Such discrimination problems occur when the hearing loss is situated on the hearing nerve rather than in the cochlear itself. This is something that cannot be obtained from tonal testing.

Half Optimised Speech Recognition Level: This is a useful measure as this shows the level which listeners can hear 50% of the speech material. This measure correlates well with the pure tone/free field average of the patient.

Using speech is a far more effective and appropriate way of evaluating a person’s listening ability as it is a stimulus which we use in every day environments. As this test can be performed in the free field it provides both a diagnostic and evaluative tool.

Speech in Noise audiometry BKB SIN/ QucikSIN

The number-one complaint we receive from people experiencing hearing loss is their inability to clearly understand speech in challenging acoustic environments yet most patient’s are tested with a just pure tones.

Cubex is one of the few audiology practices in the UK that test the cognitive processes related to hearing. Rather than just relying on a tonal stimulus to detect hearing, speech tests in quiet and in noise provide a much better ‘Real World’ perspective of a person’s reduced hearing.

It makes sense to include a speech in noise test in the test battery. Not only does it provide an understanding of a person’s capacity to process speech in noise, the measure allows us to complete a functional forecast , provides valuable information to help with hearing aid selection and is used to demonstrate improvements in aided performance.

LiSN-S PGA

We have enhanced this process further with the inclusion of the LiSN-S PGA – The new benchmark in speech-in-noise testing.

The Listening in Spatialized Noise – Sentences Test, or LiSN-S, assesses the patient’s ability to understand speech when there is noise coming from different directions. This unique diagnostic tool allows us to accurately measure how well patients understand speech in noise, before recommending the hearing technology that best fits their needs.

The LiSN-S prescribed gain amplifier (PGA) is an adaptive test that is administered under specially configured headphones where stimuli are spatially separated in a virtual 3D world that intelligently mimics a free field test set-up.

The LiSN-S PGA allows us to easily assess a patient’s spatial processing ability and determine how much difficulty they are likely to experience understanding speech in background noise. In addition to providing valuable information to help with hearing aid selection, the results of the test are also used for setting realistic patient expectations prior to hearing aid fitting and in determining when higher levels of technology may be needed.

We currently use the Eclipse with an EP15 module to perform standard threshold and neurological ABR testing. The Fmp graph functionality provides objective, mathematical and uantitative information based on multiple points within the recording to assist with waveform analysis. Use of the Fmp also provides a reduction in test time for the patient..

Electrocochleography

Electrocochleography (Ecochg) has long been available as a clinical tool for diagnosing Ménière’s disease (MD). However, due to its poor sensitivity and specificity (ranging from 20-65%) it is not often included in the clinical test battery.

Recent studies looking at measuring the SP/AP area ratio rather than the SP/AP amplitude ratio have shown that the sensitivity and specificity values associated with these measures were 92% and 84%, respectively. Cubex is currently one of the few audiology clinics in the UK that are able to measure this information, as traditional AEP systems do not have the facility to make these calculations.”

Measurement of the reduced Vestibular Evoked Myogenic Potentials (VEMP) amplitudes has also been related to the confirmation of MD.

In the past, we have found varying muscle contractions that normally occur during VEMP testing could often result in incorrect asymmetry calculations. At present, we are successfully using ‘EMG scaling’ found in the Eclipse AEP platform to avoid this potential problem. EMG Scaling ensures a balanced presentation of responses from Left and Right,” explains Adam. “This new facility allows us to successfully and accurately use the VEMP in our Ménière’s test battery.”

Ecochg, VEMP and DPOAE clinics currently run every Wednesday and Friday. If this does not suit your needs, please let us know and we will try our best to accommodate you and your patient.

Auditory processing tests

APD is a difficult to define as an international consensus does not exist. Statements have been produced to attempt to define APD from several professional bodies (BSA 2010, AAA 2010, ASHA 2005). The American Academy of Audiology (AAA 2010) APD guidelines supports the American Speech-Language-Hearing Association (ASHA 2005) definition that APD refers to a disturbance in ‘the perceptual processing of auditory information in the central nervous system and the neurobiological activity that underlies that processing and gives rise to electrophysiological auditory potentials’ (AAA 2010, ASHA 2005). This document conveys the argument that APD is a result of impaired neural function and focuses on the theory of impaired bottom up processing.

In contrast, the BSA (2010) statement suggests that ‘top-down influences’ are more related to the APD than previously thought. This has been demonstrated by Moore et al., (2010) who found that the presenting symptoms of impaired auditory processing were largely unrelated to auditory processing and factors such as attention and cognitive ability have a more significant role in this process than previously thought.

Regardless of this uncertainness there are patients attending clinic with a hearing complaint in the presence of normal hearing as determined by the pure tone audiogram. Witton (2010) provides a very comprehensive definition of APD by suggesting that patients who “present with listening disorders which cannot be explained by a problem in the peripheral auditory system or by a higher-order cognitive or language difficulty” can be classified as APD suffers.

One of the reasons why APD is difficult to define is because the interpersonal symptoms experienced by someone with APD can differ significantly. When considering APD one should think about what auditory processing consists off. The outline below (Fig 1) demonstrates the various components of APD.

Fig 1 Components of auditory processing

When looking at Fig 1 it becomes apparent that auditory processing is far more than just sending a sound along the vestibulocochlear nerve. ASHA (2005) states APD can affect the following processes:

It should be noted that there is still much intra-professional debate regarding whether these reported difficulties are actually true for this condition. For instance, a recent study by Ferguson et al. (2010) found that children diagnosed with APD or specific language disorder did not show a significant difficulty when listening to speech in steady state background noise. However it is recognised that those suffering from any of the above symptoms in the absence of a higher order cognitive or language difficulty either have a lesion or a deficit in the central auditory nervous system which is associated with abnormal behavioural or electrophysiological manifestations (BSA 2010, AAA 2010).

There are many tests designed to diagnose APD. These range from subjective measures of behavioural responses to objective tests measuring the electrophysiological responses of the central auditory system.

The AAA (2010) suggests that ‘Prior to administration of the central auditory test battery, the individual’s peripheral auditory function should be evaluated with the goal of confidently ruling out or confirming middle ear and/or cochlear auditory dysfunction. A suggested test battery for assessment of peripheral auditory function includes:

Immittance measures, including tympanometry and acoustic reflexes in uncrossed and crossed stimulus conditions

Pure-tone audiometry with air conduction stimuli at the conventional octaves, plus 3000 and 6000 Hz. Bone con¬duction may not be necessary if findings are normal for DPOAEs and immittance measures

Word recognition performance in quiet at a comfortable intensity level using recorded AB word lists. Once these tests have been performed tests of auditory processing function can be performed

Objective measures of APD:

The use of electrophysiological potentials in diagnosing APD is an exciting and developing concept. However the research which presents itself in the literature lacks the methodology and statistical power for it to be routinely applied in the clinic. Although the results from the current research are promising, the evidence base is currently uncertain of the sensitivity and specificity of these electrophysiological tests. Therefore the main method of diagnosing APD lies in behavioural measures.

Subjective measures of APD:

When testing for APD it is important to use a variety of tests which assess all areas of the central auditory system.

Recommended by AAA (2010)

Tests of Temporal Processes

Dichotic Listening (Speech) Tests

Tests of Monaural Low-Redundancy Speech Perception

Tests of Localization and Lateralization and other Binaural (Interaction) Functions